Approach Considerations
Urinalysis and urine culture can confirm the presence of infection and identify pathogens. Fractional urine studies (urethral and bladder urine) and cytology of expressed prostatic secretions can help differentiate prostatitis from urethritis and cystitis. Further studies may be indicated in patients with possible complications (eg, urinary tract obstruction). There is no gold-standard diagnostic test for chronic abacterial prostatitis. [35]
Urine Studies
On urinalysis, obtain quantitative values for the white blood count and bacterial count, presence of oval fat bodies, and lipid-laden macrophages. A urine culture can be used to identify the causative organism, if any. Escherichia coli is the pathogen most often identified on positive cultures (see the image below).
Urine culture with greater than 100,000 colony-forming units (CFU) of Escherichia coli, the most common pathogen in acute and chronic prostatitis. Chronic bacterial prostatitis must be confirmed and diagnosed using a urine culture.
Fractional urine examination
The use of fractional urine specimens may be useful in the diagnosis of prostatitis. Although not practical in most emergency departments, this technique is used by urologists if the diagnosis of prostatitis remains unclear.
The initial 10 mL of voided urine represents urine from the urethra and is termed voided urine 1 (V1). Elevated bacterial counts in V1 suggest urethritis. The next 200 mL of voided urine is discarded, and a midstream urine sample (V2) is collected, which represents bladder urine. Bacterial counts elevated in the midstream sample suggest cystitis without prostatitis.
Next, the physician performs a prostatic massage and the expressed prostatic secretions (EPS) are collected from the urethral meatus (see the image below). Finally, the 10 mL of voided urine following prostatic massage (V3) are collected. The bacterial findings of the EPS and V3 samples represent the microbiologic characteristics of the prostate gland.
Bacterial prostatitis. Expressed prostatic fluid contains more than 10 white blood cells per high-power field, indicating prostatitis.
Chronic bacterial prostatitis can be diagnosed if the culture of the EPS and V3 samples produce the same bacteria as the first-voided specimen and the colony count of the 2 cultures is at least 10 times as great as the first-void specimen.
Blood Studies
A complete blood count (CBC) with differential and blood cultures are indicated in cases of acutely toxic patients or suspected sepsis.
Obtain an electrolyte panel, including blood urea nitrogen (BUN) and creatinine values, in patients presenting with urinary retention or obstruction.
Prostate inflammation can lead to elevation of serum prostate-specific antigen (PSA). PSA is used primarily as a cancer screening tool and should not be routinely used for the diagnosis of prostatitis. [36]
Ultrasonography and Computed Tomography
Transabdominal ultrasonography or a bladder scan is used to assess for volume of retained urine in cases of prostatitis associated with significant voiding dysfunction. [21]
On transrectal ultrasonography, characteristic features of prostatitis are capsular thickening and prostatic calculi. A hypoechoic halo in the periurethral region, a heterogeneous echo pattern, and enlargement and thickening of the septa of the seminal vesicles may be seen. [37]
Interpretation of transrectal ultrasound is highly subjective and therefore not very reliable for the diagnosis of prostatitis. This study is not routinely indicated in patients with prostatitis, except when prostatic abscess is suspected.
Computed tomography (CT) studies of the pelvis also may be useful in the evaluation of prostatic abscess or suspected neoplasm. Cystoscopy is useful in refractory cases with significant voiding dysfunction symptoms to rule out neoplasm of the bladder or interstitial cystitis. Voiding cystourethrography (VCUG) or retrograde urethrography (RUG) may be appropriate for evaluation of the bladder neck anatomy and penile and anterior urethra in cases of suspected bladder neck dyssynergia or urethral stricture.
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Bacterial prostatitis. Expressed prostatic fluid contains more than 10 white blood cells per high-power field, indicating prostatitis.
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A nonspecific mixed inflammatory infiltrate that consists of lymphocytes, plasma cells, and histiocytes is typical in chronic bacterial prostatitis.
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Urine culture with greater than 100,000 colony-forming units (CFU) of Escherichia coli, the most common pathogen in acute and chronic prostatitis. Chronic bacterial prostatitis must be confirmed and diagnosed using a urine culture.
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Treatment algorithm for chronic bacterial prostatitis. Courtesy of Frontiers Media [Xiong S, Liu X, Deng W, Zhou Z, Li Y, Tu Y, et al. Pharmacological Interventions for Bacterial Prostatitis. Front Pharmacol. 2020. 11:504. Online at https://www.frontiersin.org/articles/10.3389/fphar.2020.00504/full].
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Treatment algorithm for acute bacterial prostatitis. Courtesy of Frontiers Media [Xiong S, Liu X, Deng W, Zhou Z, Li Y, Tu Y, et al. Pharmacological Interventions for Bacterial Prostatitis. Front Pharmacol. 2020. 11:504. Online at https://www.frontiersin.org/articles/10.3389/fphar.2020.00504/full].
